The present invention relates to a method for indicating malfunctions of a DC generator driven by an engine or the like.
FIG. 1 shows an example of a conventional malfunction indicating circuit for a vehicle-mounted DC generator. In FIG. 1, a DC generator 1 feeds a battery 2 and an electrical load 3 of vehicle. A switch 4, which may be a key switch of the engine, is connected in series with a charge lamp 5 used to indicate malfunctions of the DC generator 1. Also connected in series with the charge lamp 5 is a circuit breaker 6. A voltage regulator 7, connected to a field winding 8, functions to maintain constant the output voltage of the DC generator 1 by regulating the field current flowing through the field winding 8.
In operation, when the key switch 4 is turned on, the charge lamp 5 is lit by a current through the circuit breaker 6 which is held in an on state. Then, when the engine is started and the DC generator 1 is rotated, the circuit breaker 6 is turned on and the charge lamp 5 is extinguished, indicating normal operation of the DC generator 1.
When the DC generator 1 does not provide an output for some reason, the circuit breaker 6 is held in the on state and the charge lamp 5 is lit, by which an abnormality of the DC generator 1 is indicated. Also, when the voltage regulator 7 does not function correctly, for example, when the regulator 7 is maintained in the on state continuously for some reason providing no voltage regulation, the circuit breaker 6 continues to be in the on state and the charge lamp 5 is lit. This also indicates an abnormality of the DC generator 1 including the voltage regulator 7.
In such a conventional method of indicating malfunctions of the DC generator, it is impossible to know from the charge lamp whether the indicated malfunction is in the DC generator or the voltage regulator. It is, however, important to ascertain the point of the failure since a malfunction of the DC generator 1 makes it dangerous to continue to drive the vehicle because the battery is running down, which will eventually stall the engine and make it impossible to re-start the engine after the battery has been discharged to a certain level.